Generally, floppy discs are used for computers and certain office automation machines. Cassettes are used for video tape recorders.
One type of disc drive which uses these magnetic discs is designed to transfer the disc downwardly in an instantaneous manner instantaneously when it reaches a pre-set point after being inserted from an inlet. When the disc contacts the turntable as a result of the aforementioned downward motion, there is a possibility of damaging both the disc and the magnetic head.
FIG. 6 illustrates this general type of disc drive. It is comprised of a turntable 3 which draws and sustains a floppy disc (M) inserted from an inlet (2) by using magnetic force, a direct drive motor (4) which rotates the turntable (3), heads (5a, 5b) positioned above and below the floppy disk (M) to read and write records from floppy disk (M), carriages (6a, 6b) positioned above and below floppy disk (M) which support the heads (5a, 5b), a stepping motor (7) which moves the carriages (6a, 6b) in the directions of arrow A, and a spring (6c) which pulls the upper carriage (6a) downward.
A mechanism for enabling the floppy disc (M) to be moved downward after being inserted from the inlet (2) is illustrated in FIG. 7A and FIG. 7B. Referring to FIG. 7A, the floppy disc (M) is inserted from the inlet (2) and enters into a holder (8). The holder is provided with four rollers (9), one each at both sides of and at the front and rear parts of the holder (8). A slider (10) which is disposed upon both sides of holder (8) slides both forwards and backwards and is provided with a groove (11) in which the rollers (9) can slide.
When a floppy disc (M) is inserted into the holder (8) and is advanced to a pre-set position, the slider (10) is moved in the direction of arrow B by stopper members and pulling members which are not illustrated in FIGS. 7A or 7B. The slider (10) is provided with an eject button (12) which is operated from the front side of the disc drive. A pin portion (20) pinpoints and secures the floppy disc with a positioning hole (13) on the floppy disc cartridge or case. When the floppy disc moves downward and loads on the disc drive, the correct position of disc is secured.
Positioning holes (13) are provided at four corners of the floppy disc case. The pin portions (20) are located at four places corresponding to the pinpoint holes (13). Accordingly, when the floppy disc (M) is inserted from the inlet (2) and is advanced into the holder (8) to the pre-set position (FIG. 7A), the slider (10) moves in the direction of arrow B, thereby causing the holder (8) to move downward by the sliding engagement between the groove (11) and the roller (9). (FIG. 7B)
In this case, the pin portion (20) fits into the positioning hole (13) and the correct position of the floppy disc is secured. As mentioned above, when the floppy disc (M) moves downwardly in an instantaneous manner with the holder (8), and touches the lower head (5b) with some shock, there is a possibility of damaging the floppy disc (M) or the head (5b).
To avoid this shock, some manufacturers adopt an air damper which is located at the holder (8) (not illustrated on the drawing). These devices absorb shocks by a damping action. But such a damping action is not applied directly to the magnetic disc (M), but rather to the holder (8). Thus, a satisfactory damping action is not performed.